


Experiment of Three

by TellTaleKael



Series: Error’s Dolls [5]
Category: Undertale (Video Game)
Genre: ? - Freeform, Chapter two, Creammare - Freeform, Dubious Consent, Embarrassment, Error/Unknown, Error/ink - Freeform, Error’s Dolls, Hints Of Pre-Apple Dreammare, M/M, Nightmare Sans/Dream Sans/Cross Sans, Nightmare/Dream/Cross - Freeform, Not Seen But Implied, Oral Sex, Public Sex, Rape/Non-con Elements, Sex Dolls, Sibling Incest, Threesome, Unseen Error/Dream, Vaginal Sex, Voyeurism, dubcon
Language: English
Status: Completed
Published: 2021-03-09
Updated: 2021-03-10
Packaged: 2021-03-16 03:47:58
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 2
Words: 2,208
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29944014
Author URL: https://archiveofourown.org/users/TellTaleKael/pseuds/TellTaleKael
Summary: Dream is called to a universe being attacked by his brother, but what he finds is not what he expected at all.
Relationships: Sans/Sans (Undertale)
Series: Error’s Dolls [5]
Series URL: https://archiveofourown.org/series/2146278
Comments: 17
Kudos: 122





	1. Dream

**Author's Note:**

> Please note the tags, and feel free to leave if you need. Otherwise, enjoy. uwu

“I’ll go this way, Ink you sweep around the western side and let’s see if we can keep them contained in one area,” Dream called, bow out with an arrow at the ready. It had been a while since his brother had appeared during an attack, and even though Blue was busy taking care of his detoxing brother, he and Ink had to run interference. Being one member down would certainly hurt their chances, but they had to protect the remaining citizens of the universe that was in danger. 

Ink disappeared into a splash of liquid, and Dream looped around a grove of trees. The destruction was visible as soon as he made it past the trees, deep gouges in the icy ground of this universe’s Snowdin. It looked like at least two or three buildings were on fire, smoke billowing from the outskirts of the town. A blast of purple magic tinted with red flashed across the area. Dust was definitely there. It was rare for all of Nightmare’s gang to come out at the same time, one remaining back for reinforcements. Who it was varied each fight.

Dream could hear magic attacks being thrown around as he drew closer. He knew the moment he had been spotted, the emotions around him growing more focused. It looked like Error was the one who had remained behind, as the glitch was nowhere to be seen, and there were no strings draped around the surrounding area. Dust was the one setting off random attacks, with no apparent target in mind. Horror was standing to the side, leaning heavily on his axe, looking extremely bored. Killer was flipping his knives, grin wide under his empty sockets. Cross was sitting on the ruins of a stone wall, hood up over his skull. 

Nightmare wasn’t directly in view. Dream stepped forward, arrow trained on Dust. “Drop your attacks,” he commanded. Ink would no doubt pop up soon, and the gang didn’t give any indication that they were going to run. In fact, Killer’s grin widened into a laugh.

“why don’t you come make us,” he called. Amusement rolled off of him in waves.

“I will!” Dream took another step forward. Then another.

His foot wouldn’t move for a third step.

Dream struggled, but his body refused to obey, feet firmly planted on the ground. A strange thrill went through the gang, but all Dream felt himself was sharp panic. He couldn’t hold on to his arrow, the magic dissipating. “What-?” he began, sockets widening.

Pressure settled against his pelvis, rubbing in soothing circles. Dream’s knees began to shake, color rising to his cheekbones. It felt like a caress, the touch of a lover trying to excite him. Trying, and succeeding, if the magic that began to slowly collect in his pelvic inlet was any indication. 

The touch was gentle, unlike Ink who was brutally efficient in getting the results he wanted, but it was similar in that Dream could not feel the emotions of whatever was playing with him. He usually had the advantage of knowing who was touching him and why, and the lack of that was uncomfortable. 

A second touch stroked against his sternum, making him tremble even harder. He was extra sensitive along his ribcage, face growing even darker with a heated flush. He heard a whistle, and realized that Nightmare’s gang was still present. Feeling their appreciation for his aroused state was what finally did it. His ecto rose into place, his tights uncomfortable with the sudden flesh filling them out. He heard the rip at the same time his chest grew tight. His top was peeled off of him by the unseen force, baring his breasts. He could feel eyelights on his body, looking with interest as his tights were ripped from his legs. Embarrassment warred with arousal as something wet slid between his thighs, even though he could not see anything physically there. 

The bow fell from his hands as what felt like a large tongue teased over his pussy. His magic, unable to tell what his unseen partner wanted, had summoned both sets of genitals, cock rising above his slit and weeping at the head. A second tongue-like entity lapped at the bead of magic, and the first moan fell from Dream’s teeth.

“he’s into it,” came Killer’s awed chortle. Dream blushed and tried to close his legs, but his body wouldn’t cooperate.

“He is,” came a dark voice. Dream blinked and Nightmare was there, standing before him, hands in his pockets. He looked casual, as if seeing his brother naked on what was supposed to be a battlefield was a common occurrence. Dream shook at how pleased Nightmare felt.

“Brother,” he gasped as his entrance parted, the phantom tongue thrusting inside. Shame burned low in his gut, fueling the arousal into an inferno. His phalanges curled into a fist, and he tried to bite back the moans that spilled from him. Nightmare smirked.

“Yes, Dream?”

Dream shook his head, back arching as the second tongue curled around his cock, squeezing and stroking it in time with the thrusts. He couldn’t move, and at that point, he wasn’t sure he wanted to, pleasure heightening. He must have made quite a sight, assaulted by some invisible force, yet dripping wet already. It felt incredible. Nightmare’s burning eyelight pinned him, watching every minute expression he made, sucking Dream in until all he saw was the real glow.

Then, suddenly, it stopped. As if a string had been cut, Dream dropped to his knees, every touch gone. He sobbed in frustration, the peak he had been approaching slipping away. Nightmare’s brow furrowed. Dream looked up at him with watering sockets. 

“Please,” he whispered.

Nightmare was on him in seconds. Dream didn’t even notice the sounds of teleportation, too busy having his mouth invaded by Nightmare’s tongue. He only realized that the gang had disappeared when Nightmare looked over his shoulder. “Cross,” he called, the only remaining member of the gang still there. Cross obeyed the unspoken command, coming closer. Dream found himself with an armful of Cross, Nightmare pulling the soldier’s shorts down. The purple of his pussy was a shade darker than Nightmare’s used to be, but he was hot and tight around Dream’s cock all the same. Dream gasped, wrapping his arms around Cross, who blushed darkly. 

Nightmare settled against Dream’s back, and Dream cried out when his brother’s cock slid inside his stretched entrance for the first time in centuries. Cross and Nightmare moved in tandem, milking Dream’s pleasure with thrusts and squeezes, kisses and bites to his flesh, breasts and shoulders. They moved as a team, and Dream wondered when they had started sleeping together, as they moved like two monsters who knew one another intimately. He didn’t think on it too long, as it wasn’t much longer before he came, the dual points of pleasure too much for him to stand. He clung tight to Cross, and Nightmare clung to him in turn, panting for breaths they didn’t need. 

“What... was that?” Dream panted.


	2. Error

**Notes for the Chapter:**

> Mind the tags again!

Error had one of his tongues deep inside the Dream doll when Ink appeared in front of him. He startled so badly that he dropped the doll, his intent being cut off before it even hit the ground. He had been so focused on his task that he hadn’t even heard the rainbow asshole arrive. He jumped up, stumbling as his shorts were around his ankles, cock smeared with his own precum from where he had been stroking himself. He didn’t even have a mind to close the portal that looked over a naked, flushed Dream.

“I-Ink! Wh-whAt do yOu wAnt?” he spat. Ink’s eyelights swept from the portal, down to the doll, and up over Error’s state of undress. Error yanked his shorts up with one hand.

“I knew it!” Ink declared. “You’re using those dolls to screw around with people. I didn’t think you were actually screwing them, though.”

Error growled. “So wh-whAT?”

Ink looked up, spotting the very dolls they were talking about. Error threw strings out, but Ink avoided them, using Broomy to push himself up. His phalanges closed around a doll, and Error’s soul dropped.

“N-nO, not thAt oNE!” He tried to grab the Blue doll out of Ink’s hand with his strings, but the artist dances around them with practiced ease. 

“You made one of Blue? I can see Dream, he’s very kinky, but little Blue? Really, Error?”

“I’ve nEveR fUckeD tHaT OnE,” Error cried, voice glitching even worse than usual, static filling his voice. “GiVe hiM b-BaC-cK!”

Ink grinned. “I don’t think I will. Your crush is so obvious, you know.” He pet the skull of the doll with a single phalange. Glitches raced along Error’s bones. “I think I’ll keep this one. I’ve never got to taste Blue before.” Ink summoned a portal, and Error stepped forward.

“TaKe miNe inSTeAd.”

Ink paused. “What?”

Error lowered his own doll, clasping his hand around it. It hung limply in his grip. “TaKe miNe. JuSt leAve BluE alOne.”

Ink squinted at Error suspiciously. “Really?” Error nodded. “Hm. Well, if you insist.” He stepped away from the portal, towards Error. Error’s sockets didn’t leave the Blue doll, until it was safe back in his hand. He thrust his own over, which Ink plucked up gleefully. “Pleasure doing business with you,” Ink said with a cheerful smile. Error pulled the Blue doll to his chest protectively, watching Ink disappear through his portal.

“F-fuCk,” he whispered. 

***

The first day, nothing happened.

Error sat around in the anti-void, waiting for the shoe to drop. Surely Ink had plans for the doll? Going after him would no doubt force Ink to act sooner, and with Nightmare tied up hatefucking Dream all over the castle (though of course it wasn’t hate, Error didn’t even need to be able to sense emotions to know that, and Cross was also there, creating a messy group of bastards all covered in copious amounts of slime), there had been no missions or fights to force Error into Ink’s path. He knitted, missing his stitches over and over until he balled it all up and threw it away. But still, nothing happened.

The second day, nothing happened either.

By the third day, Error figured that Ink had probably forgotten the doll. It was for the best. Now he wouldn’t have to worry about it. He opened a portal to Undernovela, settling in to watch his favorite show, truly relaxing for the first time in three days.

They were in the middle of a shootout scene when Error felt it. A phalange scraped against the inside of his pelvis, and his body began to heat up immediately. He lurched forward, groaning. “F-fuCking bAstArd,” he grumbled, falling on his hands and knees. His shorts were tossed aside, that single phalange coaxing his magic to form. The tip rubbed against his magic, and it formed a wet slit at the unspoken command. Error jerked forward when an eager tongue slipped inside of him. Ink had said something about wanting to taste Blue...

Error rocked back onto Ink’s tongue. At least the shithead knew what he was doing, swirling his tongue against Error’s inner walls, stretching and caressing him. He came without even a touch to his clit, collapsing against the floor and panting. Hopefully the idiot would get bored now, and Error could steal the doll back sometime. He got up and cleaned himself off, feeling both satisfied and hollow at the same time. 

***

Error was at the castle the next time it happened. Ink fingered him to orgasm twice, then pressed a kiss to his hip. 

He was eaten out again in Outertale. Fingered in Candytale. Ink rubbed off against him while he was at home in the anti-void. Error never knew when or where he would be used, once even finger fucked during a meeting with Nightmare. That had been the final straw. Error tracked Ink down after that, stringing him up.

“WhEre iS it?” he demanded. Ink looked puzzled.

“Where is what?”

Error shook him with the strings. “The dOll, idIOt! ThE oNe yoU’ve beEn fucKinG around with. My dOll!”

Ink tilted his skull, eyelights flashing between colors and shapes. “Oh!” he said after a moment. “That doll! Right. I don’t have it.”

“WhAt?”

“I never did. I gave it away.”

“To WhO?!” Error hissed.

“I don’t remember.”

Error left Ink strung up, storming back to the anti-void. He wasn’t there long before the phalanges began to tease him, phalanges that he now knew didn’t belong to an artist.

“N-no,” he mumbled as he was pitched forward onto his knees. Practiced phalanges coaxed him to form, and he bit down on his arm. Instead of a tongue, something hard and hot pressed against his entrance. He cried out as a stranger thrust their cock inside him, stretching him wide. He was fucked into the floor of the anti-void, coming twice before he was filled. Gentle kisses were placed on the back of his skull as the stranger pulled out. Error flopped over on his side, exhausted.

Blue cum leaked out of him, smearing across his thighs and glistening in the unnatural light of the anti-void.


End file.
